Cold not all bad

Upside could include harm to pests, protection of plants, lower crime, lower weight

Eeva Kallio knows all about the cold. She grew up in Finland, and if it wasn't her turn to use the family's one pair of cross-country skis, she had to walk four miles to school in weather that was often 20 degrees below zero.

Decades later, she believes that for all the discomfort and occasional frostbite, growing up in the cold had lasting benefits.

"It was tough, but it also taught me perseverance," said Kallio, now 74 and a resident of Des Plaines. "I don't give up, no matter what happens. I sometimes do marathons, and when they get really tough, I think back to the old days in Finland."

This week's extreme temperatures have come as a shock to Chicago's system, but scientists, researchers and aficionados of the cold say the plunging mercury can have surprising benefits for human beings and the rest of the natural world.

Consider the emerald ash borer, a pesky beetle that has threatened ash trees across the state in recent years. Monday's deep freeze came tantalizingly close to the temperature needed to knock back some of the insect scourge.

The green beetles die when temperatures drop. But their spawn, countless emerald ash borer larvae, wait out the cold just beneath the bark of many ash trees, producing a kind of natural antifreeze, said Rob Venette, a research biologist with the U.S. Forest Service who has studied the bug.

Monday's record-breaking temperatures, which bottomed out at 16 below at O'Hare International Airport, might still have done in some of the larvae, Venette said, though researchers will have to wait until spring to assess the carnage.

Brenda Dahlfors, horticulture program coordinator for the University of Illinois Extension's McHenry County office, said some bulbs require a period of cold. Flowers like daffodils, she said, won't bloom in the spring if they aren't first exposed to the cold.

She said many other plants likely won't be troubled by the polar vortex since they're well-protected by snow.

"You've got plenty of insulation, so even though you might get some die-back (at the surface), the root systems are probably just fine at this point," she said.

Other cold comforts can be found in the human world. For instance, statistics suggest that crime is less prevalent when the temperature drops.

Crime rates tend to jump in Chicago during the warmer months, and national crime statistics have shown that fewer violent and nonviolent crimes are committed in colder weather, said Matthew Ranson, an economist who wrote his dissertation on the issue at Harvard University. He said he would expect crime to drop throughout the cold snap.

"We see both a seasonal pattern … where there's less crime in cold months, but we see it also on a day-to-day basis," he said.

Academics continue to disagree as to why fewer crimes might be committed in colder temperatures. One theory is that people stay inside, limiting opportunities for crimes. Some researchers have proposed a biological link between heat and behaviors that lead to crime. Ranson said he thinks the numbers support both theories.

If you're looking for one more silver lining in Chicago's arctic weather, consider this: Being cold just might help you lose weight.

That's the preliminary idea stemming from research into "brown fat," a substance distinct from the white fat that stores calories and gathers around human bellies and thighs. Brown fat, which is mostly found in small quantities around the neck and upper torso, is thick with cellular power plants called mitochondria, and it burns calories like mad.

Dr. Lisa Neff, an assistant professor of endocrinology at Northwestern University's Feinberg School of Medicine, studies brown fat and said the evidence suggests that chilly environments spark its calorie-burning power.

"There's something about the cold that activates our nervous system to get our brown fat working and generating heat," she said.

Neff said brown fat can't be singled out as an obesity killer, given the many environmental and genetic factors that also come into play. Still, it's one more reason to see the cold's bright side — though not, Neff hastened to add, when it gets to be minus 16.

"We don't need to expose people to those temperatures, so we don't," she said. "We can activate brown fat at 66 degrees."